U.S. Pat. No. 3,772,099, issued Nov. 13, 1973, to Fredrick M. Ryan and Robert C. Miller and assigned to Westinghouse Electric Corporation is incorporated by reference herewith. This patent describes fluorescent tagging means for explosives to provide post detonation information comprising (1) a spotting phosphor which can be excited by UV radiation to provide a band-type emission and (2) a coding phosphor which emits a line-type emission.
Both phosphors are incorporated into cemented phosphor grains of fine particle size which are dispersed in the explosive. After an explosion, phosphor grains can be located by UV irradiation of the spotting phosphor and the information on the coding phosphor can then be decoded.
The spotting phosphor is typically an inexpensive phosphor emitting over a fairly broad region of the visible spectrum and is used primarily as a means of locating the phosphor grain. The coding phosphor, which is generally quite costly, contains information about the explosive, such as the manufacturer and the type. This information is contained in a binary code which is established by the presence (or absence) of the specific fluorescence emissions of each coding phosphor.
While very effective for their intended use, it has been found that the hard abrasive phosphor grains greatly increase the impact and friction sensitivity of the explosive. As is obvious, this poses a serious problem particularly when the grains are to be added to normally sensitive explosives such as gelatinous type dynamites.